A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Accuracy of consumer-grade GPS/GLONASS nav.equipment?
From: Garret Cost
Date: 2017 Apr 5, 11:30 -0700
WAAS reliability or RIEM is always required to be checked prior to any IFR flight. GPS accuracy when WAAS is available is as good on the ground as at altitude. I fly SAR out of Barrow, Alaska and we use state of the art Sikorsky S92A helicopter. We have the the ability to mark a target as we fly over it on the FMS and by using GPS data he aircraft will circle into the wind and terminate to a hover a 50 feet. From there the aircraft can be trimmed right down to landing on that GPS point. Also keep in mind that aircraft flying an GPS approach can ave an approach minimum as low as 200 feet and with GPS automation can go to 50 feet above the runway. If WAAS is available proximity to the ground has little effect on accuracy. Hope that sheds some light. There may be exceptions but the are just that exceptions.
Sent from my iPhone
Is that another way of saying that you know where your launch pad is but you want to hit what you are aming at? ;-)
PS I do not think WAAS is full time for everywhere. When flying into an airport that needed a GPS approach we were required to check the avaibility of WAAS at our ETA. jdh
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